Strap stretching tool



July 13, 1965 J. A. KOCIAN 3,194,541

STRAP STRETCHING TOOL Filed Oct. 30, 1961 3 Sheets-Sheet 1 July 13, 1965 J. A. KOCIAN STRAP STRETCHING TOOL 3 Sheets-Sheet 2 Filed GM. 50, 1961 \N Q %N W QQN i WQW HQ OQ NW .EW

INVENTOR. W266 a l 0025400 Miuww n y 1965 J. A. KOCIAN 3,194,541

STRAP STRETCHING TOOL Filed 001:. 30. 1961 3 Sheets-Sheet 5 INVENTOR.

Jm QM United States Patent 3,194,541 STRAP STRETQHHQG TGOL James A. Kocian, Evergreen Park, FL, assignor to Interlake Steel Corporation, a corporation of New York Filed Oct. 31), 1961, Ser. No. 148,609 1 Claim. (Cl. 254-51) This invention relates to improvements in strap stretching tools by which a fiat metal strap may be drawn taut about a box or package or other object preliminary to uniting the overlapping ends of the strap by means of an interlocking joint or the like.

In US. Patent 2,964,295, issued December 13, 1960 to Marchand B. Hall and Robert E. Fogg, there is shown and described a strap stretching tool having a strap tensioning rotary gripping wheel or device connected to be driven by a ratchet wheel which is rotated by means of a lever through a driving pawl. As the rotary gripping wheel is driven to tension the strap, a holding or check pawl is provided to maintain tension in the strap by preand the strap stretching tool is to be removed from the strap, the grip of the rotary gripping wheel must be released from the strap. This is accomplished by projections on the handle which engage the check pawl and disengage the check pawl from the ratchet wheel to allow slight reverse rotation of the rotary gripping wheel due to the force of the strap tension. Upon this slight reverse rotation of the rotary gripping wheel, the bite of the wheel against the strap is released so that the wheel can then be pivoted away from the strap and allow the entire tool to be removed from its strap tensioning position.

It has been discovered through extensive use of tools of this type that when the check pawl is released from engagement with the ratchet wheel while the strap is under tension, as is characteristic of this tool type, the ratchet teeth on the ratchet wheel and the sharp protruding ratchet engaging portion of the pawl often break off or wear excessively at the instant of release because of the strap tension, so that pawl and ratchet wheel replacement is common, especially on high tension heavy duty tools.

It is, therefore, the principal object of this invention to provide an improved holding or check pawl design which allows the pawls to become substantially inoperative as holding pawls prior to their subsequent release from the ratchet wheel in order to relieve the loading on their ratchet engaging portions due to strap tension before their release and thereby eliminate the cause of ratchet wheel tooth and pawl breakage and wear to prolong the useful life of both the ratchet wheels and the pawls.

The general manner of accomplishing this object is to provide an improved pawl construction wherein the pawl has a knee type connection which allows it to function as a holding pawl in its normal straight position and allows it to be bent to render it ineffective as a holding pawl prior to its release from the ratchet wheel.

Other objects and advantages of the invention can be better understood upon reference to the accompanying drawings, in which FIG. 1 shows a side elevation of the improved stretching machine embodying the present invention with the operating lever in a normal operating position;

FIG. 2 shows a top plan view of the strap stretching tool illustrated in FIG. 1;

FIG. 3 is a somewhat diagrammatic ilustration ofv the use of the tool shown in FIGS. 1 and 2 during the binding of a box or package;

FIG. 4 shows an end elevation of the strap stretching tool shown in FIGS. 1 and 2;

3,l94,54l Patented July 13, 1965 FIG. 5 shows a sectional view taken on the line 55 of FIG. 1;

FIG. 6 shows a partial side elevation and a partial longitudinal vertical section through the tool illustrated in FIG. 2 when the operating lever has been moved to a position wherein the pawl is automatically released from the ratchet wheel;

FIG. 7 is a partial side elevation and a partial vertical section similar to that of FIG. 6 illustrating by the dotted lines the position of the operating lever when it is in its normal lower operating position and illustrating by the full lines the position of the operating lever when it is in an extreme position for the purpose of elevating the gripping dog from its normal gripping position;

FIG. 8 is a partial side elevation and partial vertical section similar to that of FIGS. 6 and 7, but shows the check or holding pawl in an intermediate position where it is still engaged with the ratchet wheel but rendered ineffective as a holding pawl by being bent; and

FIG. 9 shows an enlarged perspective view of the two springs associated with the ratchet wheel check pawl or detent.

As illustrated in the drawings, the invention is embodied in a strap stretching tool comprising a frame 10 having a base plate 10a adapted to rest upon a box or package or other objects to be bound. This frame is provided with an integrally formed handle 10:) which is adapted to be engaged by one hand of the operator for the purpose of holding the tool in its proper operating position on a box or package to be bound, such as the box 11 shown in FIG. 3. The base plate Illa is provided with two lateral projections or flanges 10c and 10d which are adapted to underlie the metal binding strap 12 while this strap is being drawn taut around the box or package. The strap 12 may be withdrawn from a coil 13 and it is first extended around the box or package 11 with the free end 12a thereof extending over the flange 10c and somewhat beyond that flange toward the right as viewed in FIG. 3. The supply portion of the strap, after being extended around the box or package 11, is carried over the flange 19d and above the strap extremity 12a above the flange Mic. The loop 1211 around the box or package may then be contracted manually to a considerable extent preliminary to the operation of the tool for drawing the strap taut around the box or package.

The mechanism by which the strap is drawn taut is actuated by a lever 15 which is provided at one end with a ball 15a adapted tobe engaged by one hand of the operator and which is adapted to be reciprocated in a vertical plane to actuate the strap tightening mechanism.

This actuating mechanism comprises a yoke 16 which is pivotally mounted upon a pin 17 extending through apertures in two lugs lile and 10 which are formed integrally with the base plate 10a. This pin 17 is secured in position by a small vertical pin 18 which is mounted in an aperture formed in the lug 10a so that it extends through a transverse hole formed in the pin 17. The yoke 16 has two parallel arms 16a and 16b which extend transversely to the pivot pin 17, as shown particularly in FIG. 5. The arm 16a has journalled therein the reduced portion 194: of a shaft 19 which extends loosely through an aperture formed in the arm 16]). The operating lever 15 is provided at its lower end with two spaced side plates 15b and 15c which extend between the arms 16a and 16b of the yoke and which are apertured for engagement by portions of the shaft 19. The side plate 15b is rotatably mounted upon the reduced portion 19a and the side plate 150 is rotatably mounted upon an enlarged ring portion 19b of the shaft. Between the parts 19a and 1911, the shaft w is provided with a fluted portion which has a splined engagement with a ratchet wheel 20 adapted to "ice be operated by the reciprocation of the lever 15 for the purpose of effecting the rotation of the shaft. The reduced portion 19:: of the shaft terminates in a threaded part 19d which is engaged by a washer 21 and a nut 22 for holding the shaft in position in its bearing.

The enlarged portion 19@ of the shaft which extends loosely through the aperture 160 of the arm 16b, is connected to a fluted portion 1% which has a splined engagement with the disk 25a of a cup-shaped gripping wheel 25. The arm 16!) of the yoke is provided with a cylindrical projection 16d upon which a cylindrical bearing member 26 is secured with a press fit and the cylindrical gripping portion 25b of the gripping member is journalled upon the bearing member 26, so that the member 25 is supported independently of the shaft 19 and the load on r the shaft is relieved and deflection of the member 25 is minimized. The shaft 19 terminates beyond the gripping member 25 in a threaded portion 19g upon which a washer 27 and a nut 28 are secured to hold the gripping member in driving engagement with the shaft. The cylindrical portion'ZSb of the gripping member is provided with an annular series of diagonal teeth 25c which are adapted to engage the upper side of the strap 12 above the flange 100 of theframe. This flange 1th: is provided with a recess in which there is mounted a gripping plate held in place, by a set screw 3i). This gripping plate has upwardly projecting teeth which are adapted to coact with the underside of the strap to hold it against endwise movement above the flange ltlc of the frame during the rotation of the gripping device 25 for the purpose of drawing the strap taut. During that operation, the extremity 12a of the strap remains in stationary position above the gripping plate 29a while the supply portion of the strap is moved over this strap extremity, toward the left as viewed in FIG. 3, by the rotation of the gripping wheel 25.

The rotation of the gripping wheel 25 is effected through the shaft 19 by the ratchetwheel 2%, which, in turn, is actuated by the reciprocating lever through a pawl 33 which has an arm 33a adapted to be engaged by the fingers of the operator and a tooth 33b adapted to engage the teeth Zita of the ratchet wheel 20. The pawl 33 is pivotally mounted on a pin 34 which extends between the side plates 15b and 15c of the lever 15. A coil spring 35 is mounted on the pin 34 within a slot 33c which extends transversely through the pawl 33. This spring has one arm 35a which engages a shoulder 15d on the lever and it has another arm 35b which engages one wall of the slot 330 so that the spring acts normally to move the pawl 33 into a position where the tooth 33b engages a tooth Ella of the ratchet wheel as shown in FIG. 1. In the normal operation of the tool, the lever 15 is reciprocated toward and from the handle 10b with the result that the tooth 33b of the pawl engages the ratchet wheel teeth to effect the rotation of the ratchet wheel upon the movement of the lever 15 toward the handle ltlb, but upon reverse movement of the lever, the tooth $312 then slides over the teeth of the ratchet wheel as permitted by the compression of the spring 35.

Between successive tensioning strokes of the hand lever 15, the ratchet wheel and the feed wheel are both held in the positions to which they have been advanced by means of a detent or holding pawl 37, best shown in FIGS. 2, 6 and 7, which is pivoted on a pin 38 extending between the upstanding lugs 19c and 16 in which the pin 17 is mounted. The detent 37 has a tooth 37a which is adapted to engage the teeth Zea of the ratchet wheel to hold the ratchet wheel and the feed Wheel against reverse rotation, as shown in FIG. 6. During a forward stroke of the hand lever 15 toward the right as viewed in FIG. 1, the detent 37 slides over the teeth of the ratchet wheel.

The holding detent or check pawl 37 is divided into two arms 37b which are the mounting portions of the pawl on the pin 38. The tooth 37a is pivoted on another pin 59 journalled between the two arms 37b so that it can pivot relative to the two arms. A shoulder 370 is provided on each arm 37b to limit the pivotal or angular movement of the tooth 37a relative to the arms 37 b. Two coil springs 39 and 51 are mounted next to eachiother around the pin 38. The coil spring 51 is adapted to urge the tooth 37a in a direction away from the ratchet wheel 29 relative to the arms 37b while the spring 39 is adapted to urge the tooth 37a and the entire pawl 37 toward the ratchet wheel 20. The spring 51 is provided with one end 51a which reacts against the tooth 37a and another end 51b in the form of a loop through which passes one end 3% of the spring 39. The other end 3% of the spring 3% reacts in an aperture ltlh formed in the base plate ltla. Also, the end 39a extends into an opening 37d in one of the arms 37!). With this arrangement, the tooth 37a is ordinarily-urged into engagement with a tooth of the ratchet wheel 2% to hold the ratchet wheel and the feed wheel 25 in the positions to which they have been moved, while the hand lever 15 is being returned for another stroke.

The feed wheel 25 is normally maintained in contact with the strap 12 being operated upon by means of a coil spring 4% which extends between the lug 1d) of the base lila and an arm 168 which is formed on the yoke 16 to extend radially from the axis of the shaft 19, as shown in FIG. 1. The luglllf and the. arm 16 are provided with projections 41 which hold the spring 4% in position. This spring acts normally to pivot the yoke 16 about the pin 17, toward the right as viewed inFlGS. 1, 6, 7 and 8, so that the yoke is normally moved to the position Where the peripheral surface 25b of the feed wheel will engage the upper surface of the uppermost strap seated on the flange we of the frame. This normal feeding position of the feed Wheel 25 is adapted to be regulated by an adjusting screw 43 which extends through a threaded aperture of the frame 10 to engage the lower edge of the yoke 16 at a point removed from the pivot pin 17, as shown particularly in FlGhl. Thus, the normal gripping position of the feed wheel 25 may be regulated to cause this member to perform properly upon metal straps of'variousthicknesses.

For the purpose of elevating the gripping wheel 25 away from the strap and from the flange lilc, which is desirable when the stretching toolis about to be removed from a box or package which. has just been strapped, means are provided for swinging the yoke 1-6 upwardly about the pivot pin 17 until it occupies the elevated position shown in FIG. 7. For this purpose, the pawl 33 is provided adjacent to'the tooth 33b with a cam surface 33d. The normal retracted position of the hand lever 15 is shown by the dotted lines in FIG. 7, but when the lever is swung beyond this position to that shown by the full lines in FIG. 7 the cam surface 33d engages a flat cam surface ltlg which is formed on the handle tab, so that the tooth 33b of the pawl then coacts with .a tooth of the ratchet wheel 2t to raise the yoke-fld upwardly to the position shown in FIG. 7 with the heel of the cam 33d resting on the flat cam surface. 10g.

When the lever 15 reaches this extreme position shown by the full lines in FIG. 7, the detent 37 is moved out of engagement with the ratchet teeth by the action of two arms 37b which are formed on the sides of the detent and'which are angularly disposedwithirespect to the arm of the detent so that their extremities engage shoulders 15:: which are formed on the side plates 15b and .150 of the hand lever at the ends of the arcuate surfaces 15 in the normal operation of the lever 15, the arms 3% ride over the .arcuate surface 15 without effecting the operation of the tooth 37a of the detent in engaging the teeth 2th: of the ratchet wheel, but when the lever 15 has been moved to the extreme position shown by the full lines in FIG. 7, so that the yoke 16 is elevated, the shoulders lee operate to elevate the arms 37b and thereby raise the detent 37 away from the ratchet teeth.

In order to move the tooth 33b of the pawl out of engagement with the ratchet teeth, merely by the movement of the hand lever 15, without manually operating the pawl 33, means is provided for automatically disengaging the pawl from the ratchet teeth when the lever 15 is swinging in a counterclockwise direction to the extreme position shown in FIG. 6. For this purpose, the hand lever 15 is provided with a socket 15g in which there is mounted a spherical ball 44 actuated by a coil spring 45. In the normal reciprocating movements of the lever 15, the ball 44 rides upon a cam surface 332 which is formed on the pawl 33 and the tooth 33]) moves into and out of engagement with the ratchet teeth as the tensioning of the strap proceeds. However, when the lever 15 is moved to the extreme position as shown in FIG. 6, a surface 33 on the pawl engages the upper surface of the detent 3'7 and the pawl is turned about its pivot pin 34 until the ball 44 passes out of engagement with the cam surface 33:: and into engagement with a recess 33g which is formed in the pawl between the cam surfaces 33d and 332. The ball 44 then interlocks with the shoulder at the end of the recess 33g so that the pawl is held with its tooth 3311 out of engagement with the teeth of the ratchet Wheel. This is accomplished while the operator maintains his grasp on the lever 15 and this lever may then be returned toward the position as shown by the dotted lines in FIG. 7 or the full lines in FIG. 1, with the tooth 33b of the pawl out of engagement with the ratchet wheel. As the lever 15 approaches the end of its clockwise movement, the cam surface 33d engages the flat face 10g of the handle with the result that the pawl is turned so that the ball 44 again engag s the cam surface 33c, whereupon the pawl is again moved by its spring 35 into engagement with its ratchet teeth with the lever in a new position. Thus, the operator is enabled to vary the position of engagement of the tooth of the pawl with the ratchet wheel by a one-hand operation of the lever without any manual manipulation of the pawl 33.

As previously mentioned, when the lever 15 has been moved to the extreme position shown by full lines in FIG. 7, the yoke 16 is elevated and the pawl 37 is raised away from the ratchet teeth by the shoulders 15c. The parts are so dimensioned and related that the pawl 37 is elevated and released before the yoke 16 is elevated so that the gripping wheel can reverse its rotation slightly to relieve tension in the strap at the finish of the strapping cycle. This relieves the grip of the gripping wheel 25 on the strap so that it can be raised away from the strap by movement of the yoke.

The real significance of this invention rests in the combination involving the pawl 37 which has the tooth 37a .pivoted to the arms 3712 as described. As the pawl 37 is being elevated, the tooth 37a remains in contact by the force of friction with the tooth it is then engaged with so that the tooth 37a is forced to pivot on the pin 50 relative to the arms 37b to a position as indicated in bold outline in FIG. 8. This pivotal movement of the tooth 37a allows a slight reverse rotation of the gripping wheel 25 to relieve the tension in the strap which, in effect, renders the pawl ineffective as a check or holding pawl prior to full release of the tooth 37a from the ratchet wheel 20. After this movement whereby strap tension is relieved, continued pivotal movement of the pawl 37 allows the tooth 37a to be snapped out of engagement with the ratchet teeth. Since the strap tension is released at the time of full disengagement, the sharp end of the tooth 37a or the ratchet tooth it engages have no concentrated forces applied to them to create any breakage or extreme wear condition leading to shortened life of the pawl or ratchet wheel. Consequently, pawl and ratchet wheel life are substantially lengthened over previous designs.

Although one form of the invention is shown and described by way of illustration, it will be understood that 6 it may be constructed in various other embodiments which come within the scope of the appended claim.

I claim:

The combinat on in a strap stretching device for tensioning a strap taut around an object to be bound, a frame with a pivot thereon, a link mounted on the pivot on the frame, a shaft journaled on said link, and a rotary gripping whel jonrnaled on said shaft in driving connection with the shaft, said link being rotatably movable on said pivot to thereby cause movement of said rotary gripping wheel toward and away from engagement with the strap, a ratchet wheel mounted on said shaft in driving connection with the shaft, an actuating lever journaled on said shaft and provided with a releasable driving connection with the ratchet wheel for causing the rotary gripping wheel by said driving connections to be rotated in a forward direction to tension the strap when the rotary gripping wheel is moved into engagement with the strap, and check means for preventing reverse rotation of the rotary gripping wheel in order to maintain tension developed in the strap by said wheel, said check means having a pawl engaging teeth on the ratchet wheel and resilient means urging the pawl into engagement with the teeth, said pawl being divided into a first length and a second length, the first length being pivoted to said second length to provide a jointed connection between them allowing the pawl to be bent at the connection, resilient means reacting between said first and second lengths to urge the pawl into an unbent condition, the second length being pivoted to the frame to provide a pivot for movement of the pawl toward the ratchet wheel for engagement therewith and movement away from it for disengagement, said two lengths providing a locking toggle between the engaged portion of the pawl on the ratchet wheel and the pivot for said second length to thereby provide resistance to reverse rotation of the ratchet wheel, a pawl release means on said actuating lever engageable with said second length to cause the second length to pivot away from engagement with said teeth on said ratchet wheel when the actuating lever is in a first angular relationship relative to said frame, said actuating lever in a second angular relationship relative to the frame reacting against said frame for causing said rotary gripping wheel to move away from engagement with the strap, said second angular relationship of the actuating lever being more advanced than said first angular relationship to thereby cause the pawl release means to cause the second length of the pawl means to pivot in a direction away from the ratchet wheel before the actuating lever actuates said link to cause the rotary gripping wheel to move away from engagement with the strap, said check means being bendable at the connection between the first and second lengths at this time to allow the first length to remain in engagement with the teeth of the ratchet wheel because of frictional contact between the first length and the teeth of the ratchet wheel until sufficient bending has occurred to break said locking toggle and ineflectuate the check means as a means for preventing reverse rotation of the rotary gripping wheel, reverse rotation of said rotary gripping wheel due to tension developed in said strap causing relief of the force of engagement between the first length and the teeth of the ratchet wheel to permit complete disengagement of the first length from the teeth.

References Cited by the Examiner UNITED STATES PATENTS 979,488 12/10 Heberling. 2,964,295 12/60 Hall et al. 254-51 FOREIGN PATENTS 50,165 12/89 Germany.

WILLIAM FELDMAN, Primary Examiner.

HARRISON R. MOSELEY, Examiner. 

